I am not sure that i understood what you want ...

i would answer the question:

* what is the actual size of struct inotify_event ?

inotify(7) says:
the length of each inotify_event structure is thus sizeof(struct inotify_event)+len

hope that helps ..

re,
 wh

Am 13.12.2015 13:09, schrieb Michael Titke:

Hello!

The current version of the manual page describing /inotify/ (as well as
the version installed with Ubuntu 15.04 frozen to Violet Indigo)
contains a descriptive C structure describing the /inotify//messages/:

           struct inotify_event {
               int      wd;       /* Watch descriptor */
               uint32_t mask;     /* Mask describing event */
               uint32_t cookie;   /* Unique cookie associating related
                                     events (for rename(2)) */
               uint32_t len;      /* Size of name field */
               char     name[];   /* Optional null-terminated name */
           };

As part of the development of VSI I translated the above structure
without much thinking into a corresponding byte structure description:

(define inotify-event-header
  (byte-structure-description
   (wd   int)
   (mask   4) ; [sic! that was an uint32]
   (cookie 4)
   (len    4)
   ;(name   pointer) ; That's not a pointer but an array: NAME_MAX + 1
))

Now while the prefix (or header) of the message is described adequately
the specification of the tail array as a char name[] would in C be
interpreted as a pointer onto a char. One might insert a length
parameter like char name[NAME_MAX + 1] or exclude that tail array from
the structure and describe the message in terms of /prefix/ or /header/
and /tail array/.

           struct inotify_event {
               int      wd;       /* Watch descriptor */
               uint32_t mask;     /* Mask describing event */
               uint32_t cookie;   /* Unique cookie associating related
                                     events (for rename(2)) */
               uint32_t len;      /* Size of name field */
               char     name[NAME_MAX + 1];   /* Optional
null-terminated name */
           };

With that length parameter in the structure the size of the messages is
described adequately but the actual length of the name might be confused
with the maximum size which usually includes some (tail) padding.

I'm sorry but I don't know enough about /iNotify/ to craft a patch for
this. Is this a datagram channel where half-read messages will vanish?
Perhaps I should continue reading the manual page. :-)

Regards,
Michael

-- 
VSI: https://code.launchpad.net/viper-system-interface

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PS That's not really up to the standard but "... since hosts aren't
required to relay mail at all ..." someone presumes something.
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